Interlocking mechanism



Feb. 1, 1966 M. G. CONTAL 3,233,052

INTERLOCKING MECHANISM Filed June 12, 1965 L 5 -1 J i Lf ijtf -L i3,233,052 INTERLOCKING MECHANISM Maurice G. Contal, Paris, France,assignor to La Telemecanique Electrique, Nanterre, Seine, France, acompany of France Filed June 12, 1963, Ser. No. 287,436 Claims priority,application France, Aug. 17, 1962, 907,138 8 Claims. (Cl. ZOO-50) Thisinvention relates to interlocking mechanism of the type serving toprevent the simultaneous displacement of two displaceable elements. Ithas been especially developed in connection with electrical relay andcontactor apparatus, as a safety device for preventing simul taneousactuation of a pair of contactor units eg both to contact-makingcondition.

Safety interlocking devices of this class are widely used in electricalengineering, one common instance of theirusefulness being provided bythe situation where a reversible twoor more-phase AC. motor is connectedto the power supply by way of two contactor units, the separateactuation of each of which will cause the motor to rotate in acorresponding direction by reversal of the connection between the phasewindings of the motor and the supply. Should both contactors be actuatedsimultaneously through inadvertence or accident, a short-circuitbetweenmotor phases would result and serious damage would occur.

To avoid those and similar occurences, both electrical and mechanicalinterlocking devices have been developed, the provision of a mechanicalinterlock being frequently desirable because of its more positiveaction. One common form of mechanical interlock device comprises a pairof lever arms rockable about parallel axes and mounted to be actuated bythe respective contactors on movement of the latter to actuatedcondition. In the initial or inactive condition of both contactor unitsthe two arms may be directed towards each other at an angle of about 90.Actuation of one of the contactor units will rock the related armtowards the other arm, and into engagement or near-engagement with it,whereupon it is placed in the path of rotation of said other arm therebypreventing actuation of the other contactor unit solong as the firstunit remains in its actuated condition.

It is an object of this invention to provide an improved form ofinterlocking mechanism of this general charactor, but having variousadvantages over the conventional forms such advantages including part orall of the following: reduced overall space requirements, an especiallyvaluable feature in connection with miniature electrical equipment;simplicity of the parts and ease of manufacture as well as positive andefiicient operation; similarity of both rocking components of themechanism in the case of symmetrically arranged contactor units, wherebyboth components can be manufactured simultaneously and simply mounted inmutually inverted relation; no development of undesirable stresses inthe mechanismwhen one unit is actuated and in the event of aninadvertent attempt to actuate the other, and especially no stressesthat might tend to'restore the actuated unit to its idle condition; theprovision of a simple traction spring interconnecting both componentmembers for biassing both members to their idle positions andsimultaneously acting to hold associated parts in related positions.Other objects and advantages will appear.

The invention in its chief aspect comprises interlocking arms projectingfrom the respective members in mutually crossed relation, means actuatedby each element on displacement thereof to its displaced position torock a related one of said members from a first to a second angularposition in a direction tending to move the related United States PatentO arm away from its crossed relation with the other arm, and a part oneach arm projecting towards the other arm in a direction generallyparallel to said axes and so positioned that with both members in theirfirst positions said parts are. clear of each other so that eithermember can be displaced to its second position, while with one member inits second position the projecting part thereof stands in the path ofthe projecting part of the other member whereby the latter cannot bedisplaced to its second position.

An exemplary embodiment of the invention will now be described forpurposes of illustration but not of limitation with reference to theaccompanying drawings wherein:

FIGURE '1 is a plan view, from below, showing the improved interlockapplied to a pair of associated contactor units each having a pair ofdisplaceable actuator elements in the form of vertically slidable rods:

FIGURE 2 is a sectional elevation of the mechanism on line 11-11 ofFIGURE 1; in both FIGURES 1 and 2 the electrical contactor units withwhich the mechanism of the invention is associated are shown in generaloutline only; and

FIGURE 3 is a'perspective view of one of the two similar rocking membersof the interlock mechanism.

In the drawings the interlocking mechanism of the invention is shown asapplied to a pair of contactor units C1 and C2, shown in dot-dashoutline. Each contactor unit, conventional per se, is shown by way ofexample as including an E-shaped magnetic core 1 having an energizingwinding coil 2 on its central leg, and an E-shaped movable armature 3,having its three legs registering with those of core 1, and suitablymounted above the core. Secured to the top of the armature 3 is'acruciform plate 4. To the outer ends of the laterally projecting legs ofthe plate 4, beyond the sides of the core and armature, are attachedvertically depending rods 5,-which are guided for vertical slidingmovement in respective casings 6. Both contactor units C1 and C2 aresupported on the top of a common base plate 7 having verticallydepending side flanges 7a.

On energization of the winding 2 of either of the contactor units, sayC2, the armature 3 of that unit is attracted downwardly and causes,through the resilient connection provided by the cruciform plate 4, acorresponding downward displacement of the related pair of rods 5. Inthis downward displacement, the rods 5 act to close and/or open anynumber of contact means, not

shown, provided within the casings'6. In the inoperative condition ofboth contactor units as shown in the drawings, the lower ends of bothpairs of actuator rods 5 lie substantially flush with the under surfaceof the base plate 7, while in the operated condition of a contractorunit, the related actuator rods 5 project below said under surface ofthe base plate.

The interlocking mechanism that will presently be described serves toprevent simultaneous operation of both contactor units C1 and C2, i.e.prevent simultaneous down-ward displacement of both pairs of rods 5.Such an interlock function may be required in various contexts, forinstance where the pair of contactor units C1 and C2 constitute thereverser switch means for reversing the sense of rotation of a polyphaseasynchronous motor.

The improved interlocking mechanism comprises a pair of similar rockermembers associated with the respective contactor units, and generallydesignated L1 and U2. Corresponding parts of the two rocker members aredesignated in the drawings by the same numerals followed by subscript 1or 2. The ensuing description holds for either member and the subscriptswill accordingly be omitted therein, except as required.

Each rocker member includes a rock shaft 8 having end trunnions 8apivotally received in holes formed in the opposite vertical flanges 7aof the baseplate 7. Projecting from the ends of shaft 8 in paralleldirections are similar lever arms 9, each of'which has a flat bearingsurface 9a formed at its end in a common plane. From a point of shaft 8somewhat displaced to one side from its midpoint is an arm 10- whichprojects in a direction generally opposite from that of the end leverarms 9, and at an angle thereto, as will be apparent from FIG- URES 2and 3. The arm 10 has a boss 11 formed at its end, on theside directedtowards the end of shaft 8 which is the more remote from arm 10. Theconfiguration of boss 11'will be described later. Also projecting fromthe same side of arm 10 as boss 11, but at a smaller radial distancefrom shaft 8, is a pin 13 for anchoring one end of a tension spring aswill be later described.

The two rocker members L1, L2 thus described are mounted in mutuallyinverted positions with their pivots 8a in the side flanges 7a of base7, so that the two shafts 8 and 8 are parallel in a common horizontalplane, theend arms 9 of each assembly project outwards so that the flatbearing surfaces 9a at their ends underlie the lower ends of the rods ofthe related contactor unit C1 or 02, While the intermediate arms 19 andare in crossed relation, as permitted by the displaced position at whicheach arm 10 is mounted With respect to the midpoint of its shaft '8, andthe bosses 11 and 11 are directed towards each other, so as to overlapsubstantially completely, as will be seen from FIGURE 1. A tensionspring 12 has its ends anchored to the respective pins 13 and 13 andurges the two'rockers in 0pposite directions about the axes of shafts 8S specifically in the directions tending to apply the bearing surfaces9a against the lower ends of the respective actuator rods 5.

Returning to the detailed configuration of each of the bosses 11, thisincludes a radially inner face 14 which is a portion of a cylindricalsurface coaxial with shaft 8. To one side of this inner surface 14, theboss 11 includes a lateral surface portion 15 which is alsopart-cylindrical, somewhat smaller in radius than that of surface 14. Inthe idle position illustrated in full lines in FIGURE 2, the surface 15of rocker assembly L is positioned so that its geometrical axiscoincides with that of shaft 8 of the other rocker assembly L andsimilarly the surface 15 of L has its geometric axis coinciding withthat of shaft 8 of L It is to be understood that the. geometricrelationships just described need beapproximate only, and their reasonwill presently appear.

In operation, assuming the winding 2 of contactor unit C is energized,both related actuator rods 5 are displaced downward as earlierdescribed, and their lower ends acting on the bearing surfaces 9:1 causethe rocker L to rotate as :indicated by arrow F (FIGURE 2), so I thatthe latter assumes the chain-line position shown at L In this movement,the inner surface 14 of rocker L has swept past the side surface 15 ofstationary rocker L remaining clear of said last surface owing to thegeometrical relations indicated above. In the new position of rocker L.it will be evident from FIGURE 2 that counterclockwise rotation ofrocker L is prevented, since such rotation would immediately bring theside surface 15 into abutting engagement with the inner surface 14 ofrocker L in its new position. Hence, downward displacement of theactuator rods5 associated with contactor unit C is positively prevented,even in case of inadvertent or erroneous energization of the winding ofsaid contactor.

It will be noticed that since therocker L is arrested almost immediatelyon inception of any attempted counterclockwise rotation of it due to thesmall separation present between its surface 15 and the surface 14 =ofthe deflected rocker L in its actuated position, there will be no dangerwhateverof unwanted actuation. of..any...

of the contacts provided within the casings 6 of con tactor unit C evenif the displacements required for such actuation are quite small.Moreover, in the even-t of energization of the winding of C in theactuated condition of C the only consequence will be the development oflateral reaction forces acting on the shafts 8 of both rocker assembliesL and L and such forces will not tend to rotate the rocker L in adirection to deactivate the actuated contactor unit C On deactivation ofcontactor unit C through deenergization of the winding 2 of it, therelated actuator rod 5 is restored to its idle upper position, throughrestoring spring means not shown, whereupon tension spring 12 restoresthe rocker L to its initial full-line position. At this time, the othercontactor unit C is free to be actuated, causing a symmetrical operationof the interlocking device quite similar to that described above.

It will be observed that in the illustrated embodiment, both rockerassemblies are identical and are simply mounted in positions that areinverted or positioned with respect to each other.

Various changes may be introduced into the construction shown anddescribed without exceeding the scope of the invention. Thus, if the twocontactor units to be associated by way of the interlock mechanism aredifferent rather than similar as shown, the rocker assemblies may differcorrespondingly. One or both of the rockers may be provided with asingle end lever arm 9 instead of two, or more than two may be provided.The lever arms 9 may be actuated by parts moving in rotation rather thanin axial translation as do the rods 5 shown herein. Instead of beingactuated by the moving parts of the contactors by direct engagement, asherein, they may be driven through intermediate linkage, e.g. gearsectors or otherwise.

The spring 12 may if desired be made strong enough to providesimultaneously the storing spring force for restoring both contactorunits to their idle condition. I

What I claim is:

1. Interlocking mechanism for preventing simultaneous displacement oftwo elements to respective displaced positions, comprising a pair ofmembers mounted for rocking about parallel axes, arms projecting fromthe respective members in mutually crossed relation, means actuated byeach element on displacement thereof to its displaced position to rock arelated one of said members from a first to a second angular position ina direction tending to move the related arm away from its crossedrelation with the other arm, a part on each arm projecting towards theother arm in a direction generally parallel to said axes and sopositioned that with both members in their first positions said partsare clear of each other so that either member can be displaced to itssecond position, while with one member in its second position theprojecting part thereof stands in the path of the projecting part of theother member whereby the latter cannot be displaced to its secondposition and spring means for urging each of said members towards itsfirst position.

2. Mechanism according to claim 1, wherein each of said parts has aradially inner surface which as arcuate and generally coaxial with therelated rocking axis, anda side surface which is arcuate and generallycoaxial with the other rocking axis in the first position of the relatedmember, said side surface of one member providing clearance for theinner surface of the other member when said one member is in its firstposition, and said inner surface of said one member standing in the pathof said side surface of the other member when said one member is in itssecond position.

3. Mechanism according to claim 1, wherein the means actuated by eachelement to rock the related member comprise a further arm projectingfrom said member and engaged by said element to rock the member ondisplacement of the element.

4. Incombination with a pair of contactor units each having at least onecontact actuating element displaceable to a displaced position in anactuated condition of the contactor unit, a base supporting both units,and interlocking mechanism comprising a pair of members mounted forrocking about parallel axes on said base, arms projecting from therespective members in mutually crossed relation, means actuated by eachelement on displacement thereof to its displaced position to rock arelated one of said members from a first to a second angular position ina direction tending to move the related arm away from its crossedrelation with the other arm, a part on each arm projecting towards theother arm in a direction generally parallel to said axes and sopositioned that with both members in their first positions said partsare clear of each other so that either member can be displaced to itssecond position, while with one member in its second position theprojecting part thereof stands in the path of the projecting part of theother member whereby the latter cannot be displaced to its secondposition and spring means for urging each of said members towards itsfirst position.

5. The combination claimed in claim 4, wherein said elements are rodsdisplaceable normally to said base, said members are supported on saidbase between the respective elements with each member close to itsrelated element, and wherein said means actuated by said elements torock the members comprise further arms projecting from the respectivemembers in opposite directions from one another to be engaged by therelated elements.

6. The combination claimed in claim 4, wherein said elements comprise apair of rods connected with each contactor unit. and displaceablenormally to said base, said members are supported on said base betweenthe units with each member close to its related unit, and said meansactuated by said elements to rock the members comprise a pair of furtherarms projecting from each member to be engaged by the rods of therelated unit.

7. The combination claimed in claim 6, wherein both said members aresimilar in construction, each comprising a shaft mounted in the base forrotation about a related one of said axes, said first arm projectingradially from the respective shaft at a point thereof displaced from themidpoint of the shaft, and said two further arms projecting radiallyfrom oposite ends of said shaft in parallel directions generally awayfrom said first shaft, the arrangement being such that with said membersmounted in mutually inverted positions on the base, said projectingparts of the first arms of the respective members both lie substantiallyon the mid-plane of said members.

8. Mechanism according to claim 1 wherein said spring means is a tensionspring interconnecting said arms.

References Cited by the Examiner UNITED STATES PATENTS 2,255,905 9/1941Somers et al. ZOO-98 2,262,071 11/1941 Van Valkenburg 200- MILTONKAUFMAN, Primary Examiner.

4. IN COMBINATION WITH A PAIR OF CONTACTOR UNITS EACH HAVING AT LEASTONE CONTACT ACTUATING ELEMENT DISPLACEABLE TO A DISPLACED POSITION IN ANACTUATED CONDITION OF THE CONTACTOR UNIT, A BASE SUPPORTING BOTH UNITS,AND INTERLOCKING MECHANISM COMPRISING A PAIR OF MEMBERS MOUNTED FORROCKING ABOUT PARALLEL AXES ON SAID BASE, ARMS PROJECTING FROM THERESPECTIVE MEMBERS IN MUTUALLY CROSSED RELATION, MEANS ACTUATED BY EACHELEMENT ON DISPLACEMENT THEREOF TO ITS DISPLACED POSITION TO ROCK ARELATED ONE OF SAID MEMBERS FROM A FIRST TO A SECOND ANGULAR POSITION INA DIRECTION TENDING TO MOVE THE RELATED ARM AWAY FROM ITS CROSSEDRELATION WITH THE OTHER ARM, A PART ON EACH ARM PROJECTING TOWARDS THEOTHER ARM IN A DIRECTION GENERALLY PARALLEL TO SAID AXES AND SOPOSITIONED THAT WITH BOTH MEMBERS IN THEIR FIRST POSITIONS SAID PARTSARE CLEAR OF EACH OTHER SO THAT EITHER MEMBER CAN BE DISPLACED TO ITSSECOND POSITION, WHILE WITH ONE MEMBER IN ITS SECOND POSITION THEPROJECTING PART THEREOF STANDS IN THE PATH OF THE PROJECTING PART OF THEOTHER MEMBER WHEREBY THE LATTER CANNOT BE DISPLACED TO ITS SECONDPOSITION AND SPRING MEANS FOR URGING EACH OF SAID MEMBERS TOWARD ITSFIRST POSITION.